Rusty Patched Bumblebee



Rusty Patched Bumblebees, or Bombus affinis, are a type of bumblebee. They used to be found from Ontario all the way south to Georgia and west to North Dakota, but since 2003 they have declined from 87% of their former range and are now mostly only found in Ontario. Even in Ontario they are facing extinction. Bumblebees, unlike other bees, are large, fuzzy, and carry pollen in baskets on their legs. Though female bumblebees can sting, they are pretty gentle and rarely do so unless forced to. They are, like most bumblebees, yellow and black, but their name comes from the males and worker’s rusty colored patch on the second segment of their abdomen. Rusty patched bumblebees perform a behavior called ‘nectar-robbing’, which is when they bite a hole on the outside of a flower and suck nectar with its tongue. This leaves a mark on the flower, which can help scientists know where these bumblebees live. Bumblebees in general grab the pollen producing structure and vibrate their wings, which dislodges pollen, in a process called ‘buzz pollination’. Rusty patched bumblebees live in colonies. In colonies there is one queen and many female workers. These bumblebees are between one and two centimeters long, and queens are on the larger end of this spectrum and workers at the smaller. 

Why Are They Endangered?

Recently, only a handful of specimens of rusty patched bumblebees have been found, and mostly in Ontario. Although the reason for their quick decline is not known, there are many suspected causes including pesticides, disease, habitat loss, habitat change, and possibly climate change. Pesticides often kill a lot of bees, and disease is spread from bumblebees that are used to pollinate plants in the commercial bumblebee industry. Habitat loss and habitat alteration is also a reason for their decline because it threatens their food supply. Agriculture and urban development threaten rusty patched bumblebees because it damages the flowers that produce their food and their nest sites. Livestock may also hurt habitat by removing food sources, altering vegetation and disturbing nest sites. The fragmentation of rusty patched bumblebees’ habitats diminishes populations, making inbreeding more common. Inbreeding leads to decreased genetic diversity. It’s not well documented or understood, but it is possible that parasites and climate change also adversely affect the rusty patched bumblebee. Because of all this, rusty patched bumblebees are listed as critically endangered on the IUCN red list. 



Pollinators are extremely important to the survival of plants around the planet, and are also in steep decline. Several rare plants in Ontario depend on pollinators like rusty patched bumblebees. Some plants, like tomatoes and peppers need buzz pollination to reproduce, which is another reason the decline of bumblebees is so devastating. Rusty patched bumblebees in particular are important to wildflowers, cranberries, plums, apples, alfalfa and more. Although bumblebees don’t depend on any one plant to survive, many plants do rely on bumblebees to reproduce. Where bees go extinct, the plants they pollinate decline as well.

What Can You Do?

If you live in areas where the rusty patched bumblebee still lives, it is important to report sightings. You can report photographs with locations at the Natural Heritage Information Centre. You can also volunteer locally to help. If you have a yard that you can change, you can also help rusty patched bumblebee and other pollinators. If possible, plant a lot of native flowering plants. Bees especially like pink, purple and yellow flowers. Growing a garden and adding flowering plants are really important as the areas bees can find food decrease. Even really small areas with plants are helpful. You can also leave natural areas in your yard, like leaving some unmowed places and bushy areas, which can give home to bumblebee nests. You can also make sure that you try to use as little pesticides as possible, as pesticides are very bad for bees and other pollinators.

sources cited

“Fact Sheet: Rusty Patched Bumblebee (Bombus affinis).” U.S Fish and Wildlife Service, 29 May 2019. Accessed 28 July 2020. 


“Rusty Patched Bumblebee.” Xerces Society for Invertebrate Conservation. Accessed 28 July 2020.

“Rusty-patched Bumblebee.” Government of Ontario, 8 August 2019. Accessed 28 July 2020.

*all pictures and videos used with permission, and/or taken from the sites above.

Rusty Patched Bumblebee